Haemophilus influenzae (hereinafter, the term “Haemophilus” may also be abbreviated as “H.” at times) is a causative bacterium of otitis media, pneumonia, meningitis, and bacteremia. In recent years, appearance of various resistant microbes has become a problem.
In order to detect such H. influenzae, selection via culture and a biochemical test have conventionally been used in combination. However, when selection via culture and a biochemical test are used in combination, it takes 3 or more days until infection is determined. In addition, skilled techniques are necessary for precisely selecting its colony based on its form, a difference in color, and the like. Thus, without such skilled techniques, there has been a fear of interfering with clinical diagnosis and the subsequent treatments.
On the other hand, as described in Patent Document 1, detection methods using the PCR (polymerase chain reaction) method have also been adopted in recent years.
In the case of detection in which the PCR method is used, it is common to carry out an amplification reaction using a gene characteristic of H. influenzae as a target. As such a gene characteristic of H. influenzae, a P6 protein gene encoding a P6 protein that is a surface protein has been known, for example. However, even when such a P6 protein gene has been targeted, it has still been difficult to distinguish H. influenzae from Haemophilus parainfluenzae (hereinafter abbreviated as “H. parainfluenzae” at times), which lives together with H. influenzae in the same environment and which is genetically similar thereto. Moreover, in this case, it is possible to enhance specificity by using the hybridization method in combination with the PCR method (Reference 1: T. Ueyama & four other people, “High Incidence of Haemophilus influenzae in Nasopharylgeal Secretions and Middle Ear Effusions as Detected by PCR, Journal of Clinical Microbiology,” 1995, July, pp. 1835-1838). However, it requires much time and high expenses for detection.
Furthermore, H. influenzae is classified into capsular serotypes a to f and non-encapsulated type, in terms of a difference in capsule. Of these, H. influenzae Type b (hereinafter abbreviated as “Hib” at times) is a pathogen causing serious diseases such as meningitis, epiglottitis, bacteremia, or pneumonia, particularly in children. Thus, Hib vaccine is inoculated into children in advanced countries other than Japan. However, it has been reported that Hib infection is developed after vaccination. Not only for the original purpose of discovering infection at an early stage, but also for the purpose of confirming the effect of vaccination, a Hib detection method, which is simple and excellent in terms of sensitivity, has been desired. Further, it has also been reported that Hib infection is possibly expanded in developing countries, wherein Hib vaccination has not yet been carried out. Hence, in such countries also, a Hib detection method, which is simply and rapidly carried out, is desired.
However, since phenotypic expression that is characteristic of Hib may be suppressed depending on the type of Hib, the conventional serological typing method has a risk of incorrectly diagnosing infection as negative, or of incorrectly diagnosing non-infection as positive. Thus, the conventional method provides only ambiguous results. In addition, as described in Non-Patent Document 1, there is a detection method that is based on the PCR method, but this method requires much expense in cost, effort, and time, and also requires special equipment such as a thermal cycler. Accordingly, this method has not been easily carried out in a poorly-equipped examination room in a hospital or in the aforementioned developing countries.
The present invention has been made to solve the aforementioned problems. The present invention provides a method of detecting H. influenzae, which enables accurate and rapid detection of H. influenzae and Hib, a primer set for detecting H. influenzae, and a kit for detecting H. influenzae. 
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-342268
[Non-Patent Document 1]Falla, T. J., D. W. Crook, L. N. Brophy, D. Maskell, J. S. Kroll, and E. R. Moxon, 1994, PCR for capsular typing of Haemophilus influenzae, J. Clin. Microbiol., 32: 2382-2386